JPS6214708Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thin film photoelectric conversion element array, and more particularly to the structure of a photoelectric conversion element that receives light from below a transparent substrate.

Traditionally, photoelectric conversion elements for facsimile transmitters have been MOS and CCD fabricated using IC technology.
One-dimensional arrays of are commonly used. However, there is a limit to the size of the silicon single crystal that can be created, making it difficult to lengthen the array, and in order to expand the reading width of documents, the density of photoelectric conversion elements must be increased, which increases the cost. , which also affected performance.
Furthermore, since the image from the original is reduced and formed and irradiated onto the photoelectric conversion element, a lens system for this purpose is required. In this lens system, the optical path length must be increased as the reduction ratio increases, which is disadvantageous for miniaturizing the device and requires delicate adjustment of the optical path. For this reason, close-contact reading devices that have a 1:1 correspondence between the width of the thick manuscript and the photoelectric conversion device and do not require the lens system have recently been put into practical use. Naturally, the photoelectric conversion element array needs to have a length equivalent to the width of the document, and the electrical characteristics of each element are required to be stable and uniform over the entire length.

FIG. 1 is a cross-sectional view of an example of a conventional photoelectric conversion element.

A common electrode 2 is formed on an insulating substrate 1, a photoelectric conversion material array 3 made of CdS, CdSe, Se, etc. is formed on this, and a transparent conductive layer 4 made of SnO ₂ , ITO, Al, Cr, etc. is further formed on this. Separated opaque electrode layer 5 of Au etc.
is located. The image light beam 10 from the original is irradiated from above, and the exposed portion of the transparent conductive layer 4 that is not shielded by the opaque electrode layer 5 and the common electrode 2 are opposed to one of the photoelectric conversion element arrays.
This is what makes up the bit.

However, the electrical signal level of this type of photoelectric conversion element is usually a very small value of about 10 ^-12 to 10 ^-6 , and if there is a slight pinhole in the photoelectric conversion material 3, the electrical signal will be lost regardless of the optical signal. occurs. In particular, since the area of the opaque electrode layer 5 facing the common electrode 2 is larger, dark current is more likely to occur, which has a large effect on S/N deterioration. In addition, the transparent conductive layer 4 installed on the top of the photoelectric conversion material 3 is normally formed at a substrate temperature of 300°C or higher;
Since it has an adverse effect on the photoelectric conversion material 3, it must be formed at a low temperature. As a result, a desired small value of electrical resistance cannot be obtained, and S/N, optical response characteristics, etc. deteriorate.

FIG. 2 is a sectional view of another example of a conventional photoelectric conversion element.

In this example, the above-mentioned photoelectric conversion material 3 is constructed in a bridge shape so that even if there is a pinhole, the dark current will not increase. However, the light-receiving portion is a portion facing each other without the opaque electrode layer 5 and the opaque common electrode layer 2. Therefore, in order to obtain a density of, for example, 8 bits/mm, the dimensions of the opening will be approximately 0.1 mm x 0.1 mm, and although the dark current will decrease, the bright current will also decrease, and as a result, the S/N will not improve. It can't be achieved.

In addition, since both structures have high-density wiring, a protective coat is required over the entire surface of the substrate in order to obtain environmental resistance. However, when light is received from above the substrate, it is necessary to use a transparent material as the protective coating material, and if the film thickness is not strictly controlled, variations in sensitivity will occur. Therefore, the materials to be used are limited and the manufacturing technology becomes more complicated, making it difficult to lower the price and improve the performance.

The purpose of this invention is to eliminate the above drawbacks, improve photoelectric properties,
It is an object of the present invention to provide a thin film type photoelectric conversion element array which has significantly improved cost, reliability, etc., and which can be put to practical use.

The thin film photoelectric conversion element array of the present invention includes an insulating transparent substrate that receives light from the bottom surface, a transparent conductive film provided on the top surface of the substrate and covering at least a light receiving section, and an opaque conductive film having a band-shaped opening in the light receiving section. a common electrode consisting of two layers with a film, an insulating layer provided to cover at least the common electrode other than the band-shaped opening of the opaque conductive film, and a transparent conductive film in the insulating layer and the opening. The photoelectric conversion material film is provided on the photoelectric conversion material film and has a width at least wider than the common electrode, and a plurality of signal extraction electrodes are provided on the photoelectric conversion material film and are arranged separately.

According to the present invention, since there is an insulating layer on the common electrode other than the light receiving part made of a transparent conductive film, for example, even if there is a pinhole in the photoelectric conversion material film other than the light receiving part, it can be blocked by the insulating layer. There is no increase in dark current. Further, since the transparent conductive film is provided before forming the photoelectric conversion material film, the temperature of the substrate can be sufficiently raised. Therefore, a transparent conductive film with low resistance can be obtained. Therefore, the S/N and optical response, which were problems in conventional photoelectric conversion element arrays, are improved, and in addition, since light is received from below the substrate, the protective coat for environmental resistance is particularly transparent. It is not necessary and can be applied sufficiently thickly to the wiring and photoelectric conversion material film formed on the upper surface of the substrate. Moreover, even if there is non-uniformity in the film thickness, it does not affect the photoelectric characteristics in any way.

Next, embodiments of the present invention will be described using the drawings.

FIG. 3 is a sectional view of an embodiment of the present invention.

Cr on the insulating transparent substrate 11 made of glass,
An opaque metal layer 12 such as Ta or Al is deposited to a thickness of about 1000 Å, and a band-shaped opening is provided. moreover,
A transparent conductive layer 13 made of ITO, SnO ₂ or the like is installed only in this opening portion, and each is electrically connected at the edge of the opening. Next, an insulating layer 14 made of SiO ₂ , Al ₂ O ₃ , Si ₃ N ₄ or the like is provided to a thickness of approximately 5000 Å in a region covering at least the metal layer 12, and is placed on the transparent conductive layer 13, that is, in the light receiving area. A window for forming the metal layer 12 is provided corresponding to the opening of the metal layer 12. Further, for example, an amorphous silicon film 15 is formed on this, and a high-density wiring electrode 16 for extracting electrical signals is placed thereon. Since the photoelectric conversion element array having such a structure receives the image light beam 10 from the original from below the substrate 11, the opaque metal layer 1
Since the structure can sufficiently block light so that unnecessary optical signal current does not enter from other than the opening 2, a sensor with high resolution can be obtained.

The dark current that flows between the high-density wiring electrode 16 and the metal layer 12 sandwiching the amorphous silicon film 15, which is a photoelectric conversion material film, which is a major cause of deterioration of S/N, is caused by the insulating layer 14 between them. By interposing the signal, the signal is significantly reduced, and the S/N can be significantly increased. The effect becomes apparent when the film thickness of this insulating layer 14 is about 1000 Å, and as it increases, it becomes more stable.
Almost saturated at 5000 Å or more. On the other hand, if the thickness is 2 μm or more, cracks may occur in the photoelectric conversion material film, or a long time may be required for generation by sputtering, so it is not very meaningful.

FIG. 4 is a cross-sectional view of another embodiment of the present invention.

An opaque metal layer 22 for blocking the image light beam 10 from the original to prevent unnecessary optical signal current from being mixed in is formed after the transparent conductive layer 23 is installed. Creating such a structure usually requires a fairly sophisticated manufacturing technology to ensure the conductivity and transparency of the transparent conductive layer 23, and patterning it is very difficult because it is transparent. Therefore, after confirming the performance as a common electrode when only the transparent conductive layer 23 is formed on the insulating transparent substrate 21, the insulating layer 24 and the amorphous silicon film for reducing dark current are formed. 25, high-density wiring electrodes 26, etc. can be formed. Further, the insulating layer 24 is provided with a window corresponding to the light-receiving opening provided in the opaque metal layer 22. At this time, when performing chemical etching using, for example, hydrofluoric acid, the surface of the transparent conductive layer 23 is reliably etched. Etching of the insulating layer 24 is completed, and even if the etching is a little excessive, the surface of the substrate 21 will not be damaged, and there is no need to consider scattering of the image light beam 10.

The photoelectric conversion element array has a signal level of 10 ^-12 ~
Since the dark current is very small at about 10 ^-6 A, the measures taken to reduce the dark current according to the present invention are extremely effective in improving the S/N ratio and substantially increasing the sensitivity. Further, the increase in dark current due to temperature changes is also reduced, and even if there is a circuit device in the vicinity that is accompanied by a temperature rise, it is possible to sufficiently exhibit its performance.

If the thin-film photoelectric conversion element array according to the present invention is used in a facsimile transmitter, for example, the amorphous silicon photoelectric conversion material film can be easily formed into a long length, making it possible to create an A4 format that eliminates the need for a reduction lens system.
Close-contact image sensors for B4 and B4 formats will now be available at low cost, with high sensitivity, and with high reliability.

As explained in detail above, according to the present invention,
The effect is that the photoelectric characteristics and reliability are improved, and a low-cost photoelectric conversion element array can be obtained.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of an example of a conventional photoelectric conversion element.
FIG. 2 is a cross-sectional view of another example of a conventional photoelectric conversion element.
FIG. 3 is a cross-sectional view of one embodiment of the present invention, and FIG. 4 is a cross-sectional view of another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Insulating substrate, 2... Common electrode, 3... Photoelectric conversion material row, 4... Transparent conductive layer, 5... Opaque electrode layer, 10... Image light flux, 11... Insulating transparent substrate, 12... ...Metal layer, 13...Transparent conductive layer, 14
... Insulating layer, 15 ... Amorphous silicon film, 16 ... Wiring electrode, 21 ... Insulating transparent substrate, 22 ... Metal layer, 23 ... Transparent conductive layer, 24
... Insulating layer, 25 ... Amorphous silicon film, 26 ... Wiring electrode.

Claims (1)

[Claims for Utility Model Registration] (1) An insulating transparent substrate that receives light from the bottom surface, a transparent conductive film provided on the top surface of the substrate and covering at least a light receiving part, and an opaque conductive film having a band-shaped opening in the light receiving part. a common electrode consisting of two layers with a film, an insulating layer provided to cover at least the common electrode other than the band-shaped opening of the opaque conductive film, and a transparent conductive film in the insulating layer and the opening. It is characterized by comprising a photoelectric conversion material film provided above and having a width at least wider than the common electrode, and a plurality of separately arranged signal extraction electrodes provided above the photoelectric conversion material film. Thin film photoelectric conversion element array. (2) In the thin film photoelectric conversion element array described in claim (1) of the utility model registration claim, the thickness of the insulating layer is
Those with a diameter of 0.1 μm or more. (3) In the thin film photoelectric conversion element array described in claim (1) of the utility model registration, the photoelectric conversion material film is made of amorphous silicon.